A brief description of using ultrasonic was given to test loosened rock circles and the existing problems were discussed such as uphole, suction expansion hole and water leakage hole presented in the water coupling testing through the analysis of the mechanism of probe coupling based on the ultrasonic reflectivity theory. It was compared and analyzed that the method of sealing water injection, coupling methods of cream coupling agent, capsule ultrasonic probe and a new coupling method of three-capsule ultrasonic probe was proposed and it was successfully used in the engineering applications for Pingshuo coal industry limited liability company, China. The result showed that this method was simple, convenient and feasible.